Simplified Common Lisp reference
concatenate
Symbol class: Sequences (Lists, Strings) and Arrays
Syntax:
Symbol type: function
concatenateresult-typeseqs(one or more) => sequence
Argument description:
result-type sequence type specifier or NIL
seqs sequences

CONCATENATE creates new sequence and fills it with data from arguments. See also MAPCAN.

(concatenate 'string "hello" " " "world") => "hello world"
(concatenate 'list "hello" " " "world") => (#\h #\e #\l #\l #\o #\  #\w #\o #\r #\l #\d)
(concatenate 'vector "hello" " " "world") => #(#\h #\e #\l #\l #\o #\  #\w #\o #\r #\l #\d)
(concatenate 'vector '(1 2) '(3 4)) => #(1 2 3 4)
Function indexFull documentation for concatenate (HyperSpec)